Chromatography Forum

Hello,

Over the past few months, my colleagues and I have noticed an increase in the abundance of m/z 93 in certain samples and reference standards we are running. We are using an Agilent 5975C MSD, and when we re-run these samples on our other instruments, the 93 ion does not appear. Does anyone have any information on where it's coming from or what to do to get rid of it? Unfortunately, it is affecting some compound identifications.

Thanks!

We had a similar problem - not just 93 in our case but it turned out to be the use of a cleaner near the room where the instrument was kept. 93 is the most abundant ion in many terpenes often found in floor cleaners etc. If this instrument is in another area or for some reason your samples on that instrument are more susceptible this might be something to look into.

Thank you for your response! The instrument we're having an issue with is located next to another instrument, which we aren't seeing high abundances of 93 on. My initial thought was that there was something wrong with the MS, but at this point, I won't rule anything out.

Thank you for your response! The instrument we're having an issue with is located next to another instrument, which we aren't seeing high abundances of 93 on. My initial thought was that there was something wrong with the MS, but at this point, I won't rule anything out.

Have you removed the column and used a no hole ferrule to cap off the MS and see if the 93 ion is still in the background?

If not, then there could be some type of contamination in the column, if it is then there is contamination in the MS.

Thank you for your response! The instrument we're having an issue with is located next to another instrument, which we aren't seeing high abundances of 93 on. My initial thought was that there was something wrong with the MS, but at this point, I won't rule anything out.

Have you removed the column and used a no hole ferrule to cap off the MS and see if the 93 ion is still in the background?

If not, then there could be some type of contamination in the column, if it is then there is contamination in the MS.

I have not done that, but the column was changed within the last month. We were seeing this issue with our old column as well, so I'm inclined to think it is an issue with our MS. Any suggestions on how to deal with contamination in the MS?

I would also recommend capping the MS and scanning for 93, just to be certain it's coming from the MS. Then, if it remains, start with routine maintenance, change filaments, clean source, I would also suggest changing out the repeller insulators while you're at it, especially if they're over a year old. Keep the transfer line capped, pump down, and see where you're at.